√x³+6x²y+9xy²+√9x³+6x²y+xy²
=√[x(x+3y)]²+√x[(3x+y)]²
=√x * (x+3y+3x+y)
=4√x *(x+y)
=4√1/2 *(1/2+3)
=2√2 * 7/2
=7√2
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